1. Technical Field
This invention is generally related to methods for the isolation and/or purification of nanomaterials, such as nanowires.
2. Description of the Related Art
Recently, nanomaterials have been the subject of enormous interest. Nanomaterials, notable for their extremely small size (i.e., on the order of nanometers) can be prepared from various materials, including carbon, metals, ceramics, polymeric materials and composite materials. As a result of recent improvements in technologies to image and manipulate these materials, the nanomaterials field has seen a huge increase in funding from private enterprises and government, and a number of companies have been founded based on nanotechnology.
Nanomaterials have been proposed for use in a number of commercial applications, including electronic devices, miniature batteries, biomedical uses, packaging films, superabsorbants, armor, and automobile components. More recently, nanomaterials (e.g., nanowires) have been shown to be useful catalysts in industrially important reactions, such as the oxidative coupling of methane (PCT Pub. No. WO 2011/149,996). Accordingly, methods for the preparation of nanomaterials at commercially relevant scales are becoming increasingly important.
There are many known methods for preparing nanomaterials. Such methods are generally divided into two types: physical methods and chemical methods. Generally, the physical methods include, for example, chemical or mechanical polishing methods and high-energy ball milling methods. The chemical methods include, for example, chemical vapor deposition, sol-gel methods, hydrothermal synthesis and template-directed synthesis. Regardless of the method of preparation, nanomaterials are generally isolated via centrifugation since their small size typically results in suspensions or slurries which cannot be isolated by other means. Unfortunately, centrifugation is not a viable method for isolation of nanomaterials at commercially relevant large scales (kg to ton quantities) since the physical size of known centrifuges that are capable of separating such materials significantly limits their throughput.
Accordingly, there remains a need in the art for methods for isolating nanomaterials at commercially relevant scales, for example methods for the isolation of nanowires at large scales. The present invention fulfills these needs and provides further related advantages.